Flexible filtration boom



United States Patent [72] Inventor Calvin L. Kain [56] References Cited1325 Roc'kdale, Bartlesville, Oklahoma UNlTED STATES PATENTS 74003 1 12,330,508 9/1943 McColl 210/242 :1 3,221,884 12/1965 Muller 210/242 ii}j'f #:33 3,499,291 3/1970 Mikkelsen 61/1 I a e FOREIGN PATENTS 829,7563/1960 Great Britain 61/] Primary Examiner- Samih N. Zaharna Att0rneyJ.E. Phillips [54) FLEXIBLE FILTRATION BOOM W 10 Claims 4 Drawing FigsABSTRACT: A flexible weighted net is supported in a vertical [52] U.S.CI 210/242, position by at least one horizontally elongated floatationunit.

61/] A flexible layer of hydrophobic, oleophilic material is at- [SI]lnt.Cl B0ld 33/00 tached to the net to generally conform to the positionand [50] Field ofSearch 6l/l; movement of the net. Water passes throughthe filter layer 2 I01] 70, 242 while liquid hydrocarbons are blocked.

Patented Ndv. 3, 1970 Shoot g at 2 I INVENTOR.

Patented Nov. 3,1970 v 3,537,587- .1

4 yam INVENTOR.

FLEXIBLE FILTRATION BOOM This invention is directed to apparatus forpermitting a flow of water while preventing passage therethrough ofhydrocarbon materials.

Oil slicks on bodies of water occur from accidental or intentionaldischarges from ships and shore installations, leaks from underwaterpipelines, leaks in the ocean floor from oil bearing formations, andother causes. It is frequently necessary to skim oil slicks in harborareas. However, present skimmers encounter considerable resistance inbeing towed through the water and are difficult to "handle. It has alsobecome desirable to contain oil slicks resulting fromunderwater leaks orleaks from injured vessels. However, the great majority of boom systemsproposed for such use survive for less than a day in rough seas. Inaddition, many of the more rigid boom systems do not conform to thecontours of the waves sufficiently fast to prevent the passage of oilbeneath sections which are left hanging in the air.

lt-has now been discovered that these disadvantages can be avoided byutilizing a flexible weighted net supported substantially vertically inthe water by at least one horizontally elongated floatation unit, withat least one flexible layer of hydrophobic, oleophilic material attachedto the net to generally conform to the position and movement of the net.

Accordingly, it is an object of the invention to provide a new andimproved apparatus for containing oil slicks. It is an object of theinvention to provide an oil barrier which can be readily assembled andeasily towed through water. Another object of the invention is toprovide a flexible boom which rapidly conforms to changes in thecontours of the water surface. Yet another object of the invention is toprovide a flexible oil boom having sufficient strength to endure throughlong periods of rough seas.

Other objects, aspects and advantages of the invention will be apparentfrom a study of the specification, the drawings and the appended claimsto the invention.

In the drawings:

FIG. I is an elevational view of a portion of a boom system inaccordance with one embodiment ofthe present invention;

FIG. 2 is a plan view ofthe boom of FIG. 1;

FIG. 3 is an elevational view in cross section taken along line 33 inFIG. 2; and

FIG. 4. is a diagrammatic representation of the boom system of FIG. 1forming an oil retention barrier around an offshore drilling rig.

Referring now to FIG. 1', the flexible filtration boom 11 is shown withan end section 12 and an intermediate section 13. The intermediatesections 13 are identical to the end sections 12 except for the grommets14. A- cable 15 can be used to tow the boom by the end or to anchor theend ofthe boom. An additional cable (not shown) can also be utilizedwith the lower grommet, if desired. Each boom section comprises at leastone horizontally elongated flexible floatation unit 16. While thefloatation units 16 can be employed in single serial array, it ispresently preferred to. utilize a serial array of parallel pairs offloatation units located on opposite sides of the barrier wall member17, as illustrated. The barrier wallmember 17 is supported in asubstantially vertical position by the pairs of floatation units 16 whenthe boom is placed in a body of water.

As illustrated in FIG. 3, the vertical barrier wall 17 comprises aweighted net having horizontal members I8 and vertical members 19. Theterm weighted net" indicates that the net, either by the weight ofmembers 18 and 19 or by the use of additional weights at the bottomthereof, has a specific gravity significantly'greater than that of waterso that the net acts as ballast to maintain wall member 17 substantiallyvertical. Members 18 and 19 can be steel cables which are interwoven oroverlaid and welded to each other. The net can be woven of relativelylight material, such as polypropylene rope, provided that additionalweightis added to the net to meet the ballast requirements.

It is presently preferredthat the upper portion of barrier wall 17extend upwardly from the surface ofthe body of water a greater distance,than the floatation units Thus, where curved surfaces of the floatationunits permits the surface water and/or oil to be swept upwardly and overthe floatation units by wave action, the higher projection of thebarrier wall 17 prevents such washover from passing over the boom. Thedeflected spray passes freelydownwardly between barrier wall 17 andfloatation units 16. The portion of the weighted net which extends abovethe surface 21 of the body of water can be provided with additionalstiffening means 22 to further assist in maintaining the exposed portionof the barrier wall in a substantially vertical position. One particularsuitable stiffening means which provides the desired upright rigiditywhile permitting flexibility in other directions and is readilyavailable is chain link fencing. However, any other suitable stiffeningmeans can be employed.

At least one layer 23 of flexible filtering material is positionedgenerally coextensive with the weighted net. in a presently preferredembodiment the filtering material extends downwardly along one side ofthe weighted net to a point below the lowermost portion of the weightednet and then upwardly along the opposite side of the weighted net toform a loose fitting envelope for the weighted net. The adjacentvertical ends of the filtering material can be secured together by anysuitable means, for example by lacing or by thermal bonding whereappropriate. Similarly the upper horizontal edges of the filteringmaterial can be secured together or to the adjacent portion of theweighted net. However, the filtering material can be associated with theweighted net in any manner which causes the filtering material toconform generally to the verticalpositioning and movement ofthe net.

The layer of filtering material can be formed of any suitablehydrophobic, oleophilic material, having a plurality of passagewaystherethrough. By its nature of not being wetted by water, the filteringmaterial will readily permit the flow of water through the passageways.However, due to its selective affinity for hydrocarbons, oil will adhereto the filtering material and will not pass through the passageways.While any suitable hydrophobic, oleophilic material can be utilized, thecrystalline, normally solid polyolefins are particularly useful. Theseinclude polymers and copolymers of monomers having the formula Bgfiggfiwherein R is selected from the group consisting of hydrogen or alkylshaving from l to 8 carbon atoms. Specifically, this includespolyethylene, polypropylene, ethylene-butene copolymers and the like.All liquid hydrocarbons which are immiscible with water will beprevented from passage through the filtering material while water willflow relatively easily therethrough. While the filtering material canbein the form of granules encased within permeable fabrics, it ispresently preferred that the filtering material be in the form of aself-supporting fabric of fibers of normally solid polyolefin. Thefabric can be either woven or nonwoven. If desired, the portion of thebarrier wall 17 extending above the surface of the body of water can beprovided with a film covering 24 which is impermeable to both water andliquid hydrocarbonaceous matter. This minimizes stresses on the verticalrigidity of the upper portion ofthe barrier wall by preventingaccumulations of water, oil or other matter. The cover 24 can be securedto the filtration layer 23 by any suitable means, for example by the useof polypropylene rope lashing 25.

Floatation units I6 are preferably in the form of waterproof plasticcylinders 26 filled with particles 27 of material having a specificgravity less than 1, for example a cylinder formed of vinylsheeting andfilled with foamed polystyrene particles and air. The plastic cylinders26 can be encased in a fine mesh 28 whichis capable of retaining theparticles 27 in the event ofa rupture of cylindrical tubing 26. Thecylinder 26 can be formed from sheeting with the edges overlapping toform an outwardly projecting flange 31. The flange can be provided withouter covering members 32 to provide additional strength and to securethe net 28. The outeri'members 32 can be secured to the flange 3 by anysuitable means, for example by lashing 33. The floatation units 16 aresecured at closely spaced intervals to the weighted net in barrier wall17 by suitable means, for example snaphooks 34 and eyebolts 35, toprovide substantially continuous support of the vertical barrier wall17. This permits an easy removal of one of the floatation units'andreplacement with a new unit while the boom is on location. While eachelongated flexible floatation unit is preferably in the form of aflexible cylinder, it can be composed of a plurality of individualspheres, cubes or other shapes, spaced sufficiently close together toeffect substantially continuous support of the vertical barrier wallmember.

- Adjacent sections of the boom can be secured together by overlappingthe adjacent ends and fastening the overlapped ends by placing U-bolts36 around opposing vertical members 19 of the weighted net in eachsection. These U-bolts can be utilized only in the upper half of thebarrier walls to provide greater flexibility along the length of theboom.

Referring now to FIG. 4, the boom system 41 comprises a plurality ofboom sections serially connected in a rough circle around an offshoredrilling rig 42. The end sections are spaced slightly apart to permitthe free ingress and egress of boats, but can be closed quickly in theevent of the formation of an oil slick within the circle. Buoys 43 areprovided at intervals along the length of the boom, and are preferablyin pairs positioned on opposite sides of the boom. The buoy cables canbe secured to U-bolts 36 or other suitable securing means can beprovided.

in one particular embodiment of the invention corresponding to thedrawings, each boom section was 100 feet in length and 8 feet in height.Five pairs of floatation units were provided for each section. Eachfloatation unit was 14 inches in diameter and 18 feet in length andfilled with foamed polystyrene. The weighted net was woven of Aainchdiameter steel cable at 8 -inch spacings. The filtering material was anonwoven fabric of polypropylene fibers and encased the weighted net, asillustrated in FIGS. 1 and 3. The barrier wall extended 2%: feet abovethe surface of the water. This boom system was towed to an oil-drillingrig approximately 6 miles from shore and installed for a period of 12days. Despite several storms during this period, the boom remainedintact and performed satisfactorily to confine an oil slick within itsboundaries. The extension of the filtering layer for feet below thenormal water level maintained a filtering barrier elongated floatationunit when said boom is placed in a body of water, at least one layer offlexible filtering material, said layer of flexible filtering materialbeing associated with said weighted net to conform generally to thevertical positioning and movement of said weighted net, said layer offiltering material being formed of hydrophobic, olcophilic materialhaving a plurality of passageways therethrough permitting the flow ofwater through said boom while preventing the flow of liquidhydrocarbonaceous matter through said boom.

2. A boom in accordance with claim 1 wherein said flexible weighted netforms part ofa vertically positioned flexible barrier wall member, andwherein at least two horizontally elongated flexible floatation unitsare secured on opposite sides of said barrier wall member to supporttherebetween said barrier wall member substantially vertically in a bodyof water with said barrier wall member extending upwardly from thesurface of the body of water a greater distance than said at least twohorizontally elongated flexible floatation units.

3. A boom in accordance with claim 2 wherein the portion of said barrierwall member extending above the surface of said body of water is formedof a material which prevents the passage therethrough of water as wellas liquid hydrocarbonaceous matter.

4. A boom in accordance with claim 2 wherein said layer of flexiblefiltering material comprises fibers of a normally solid 'polyolefin.

5. A boom in accordance with claim 2 wherein said layer of flexiblefiltering material comprises a nonwoven fabric of polypropylene.

6. A boom in accordance with claim 5 wherein said nonwoven fabricextends downwardly along one side of said weighted net to a point belowthe bottom of said weighted net and then upwardly along the oppositeside of said weighted net to form a loose-fitting envelope for saidweighted net, the adjacent end edges of said fabric being securedtogether.

7. A boom in accordance with claim 6 wherein said weighted net is wovenof steel cables the portion of said weighted net extending above thesurface of said body of water being provided with stiffening means tomaintain the portion of said barrier wall extending above said surfaceof said body of water in a substantially vertical position.

8. A boom in accordance with claim 7 wherein said stiffening meanscomprises chain link fencing.

9. A boom in accordance with claim 1 wherein each said elongated,flexible floatation unit comprises a generally cylindrical watertighttubing filled with particles ofmaterial having a specific gravity lessthan l.

10. A boom in accordance with claim 9 wherein said particles are foamedpolystyrene.

